1. Field of the Invention
The invention relates to prefabricated, light-weight, plaster relief forms to provide quick, low cost, installation of support members for constructing plaster coated decorative xe2x80x9cplant-on""sxe2x80x9d or xe2x80x9cbump-outsxe2x80x9d to the outside walls of dwelling structures.
2. Previous Art
Ornamentation and decoration of building structures such as residences and businesses is one important aspect of architecture. Marketing and sale of residences is enhanced by additional decorative detail. Pride of ownership is also enhanced by improved appearance of one""s building or residence. Ornamentation and decorative details are used extensively to add desirability and attractiveness to structures.
In certain regions of the country, such as the West and Southwest, the homes in the Mission style, and the Mediterranean style are quite popular. One of the popular methods of ornamentation used for these styles of homes is referred to in the building trades as xe2x80x9cplant-onsxe2x80x9d or xe2x80x9cbump-outsxe2x80x9d. The plant-ons may extend for a considerable length along the horizontal or vertical dimension of a wall or walls of a home or business. The plant-ons add a band or bands of relief to an otherwise blank facade that is presented by an unbroken expanse of plaster or stucco. The bands may extend completely around the outside perimeter of a building. For a conventional home of 2500 sq. ft., this may amount to 300-500 ft of bands for one single layer. The support for these bands are generally made of overlapping wooden boards including a first layer of 2xc3x9712 inches and a second layer of 2xc3x978 inches. The boards are placed end to end in standard lengths of 8 to 12 ft to create a continuous relief band around the home. Similar bands may be constructed around door and window openings.
Attractive relief borders around windows and doors are also used to provide enhancements to the architecture of homes and buildings. Such window and door borders have been constructed using the above methods and materials.
These features are not necessary to the structural integrity of the building, but do add a pleasing visual aesthetic appearance to a home or business.
One example of architectural relief products for attachment to homes are pre-shaped foam members such as cornices, bases, sills and balusters, for example, supplied by High Tech Foam Products, Inc of Corona, Calif. Foam members may be provided in a wide variety of shapes and sizes. The disadvantage of these members as supports for relief bands include the expense of the items themselves, on the order of $5 to $6 per linear foot, and the additional labor and material involved in adding a layer of screening or lath material over the foam to provide a matrix for the plaster to adhere.
A conventional method of construction of plant-ons uses one or more planks of overlapping boards attached to a wall at a particular height. To achieve a continuous band or strip of relief, multiple lengths of uniform cross section boards are aligned end to end and attached to the studs of a prepared wall. For conventional construction, the studs must be no more than 24 inches on center, or less, according to the applicable local, state or national building codes. The attachment is done with hammer driven nails, power gun driven nails, large staple guns or the like. The boards are attached to the wall prior to the application of a plaster coat or coats and prior to the application of a lath sheeting which will form a matrix or lattice for supporting the plaster when it is applied. The lath is conventionally made of chicken wire or expanded metal and attached with nails, staples or the like. The lath sheeting may be suspended away from the wall and boards by a furring strip or strips interposed between the surface of the wall and the sheeting. Self furred sheeting or wire may also be used to maintain the spacing between the wall and the sheeting. An example of such wire is self furred metal lath made by California Expanded Metal Products Company of Industry, CA. xe2x80x9cDimpledxe2x80x9d or ribbed type self furring metal lath provides a xc2xc inch indentation in the metal lath to hold it away from the wall allowing the plaster to fill the space between, insuring the lath is embedded. The spacing between the lath and the wall or boards provides the opening for the plaster coat to surround the lath and thereby bond firmly to the wall. A moisture barrier layer, of building paper, for example, is applied between the boards and the lath sheeting by means of staples, nails, an adhesive coating or the like.
The boards provide the relief pattern or bump-out desired. Additional screening is cut and shaped by hand to conform to the protruding bump-out and nailed or stapled to the boards and the wall.
Plaster is then applied to the bump-out and the wall to form the finished surface.
With reference to FIG. 10A, there is shown a schematic diagram of an exploded view of one previous art method of assembly for a manually fabricated plaster relief form as described above. A plurality of boards of desired width with the same cross section are aligned end to end and nailed to the prepared wall to form a continuous plaster relief band to the desired length. Additional lengths of wire screen or lath sections may be placed over the boards and formed by hand to the contour of the boards. The additional sections are then typically nailed in place. FIG. 10B illustrates a cross section of such a relief form having a board attached to a stud framed wall. A layer of moisture barrier paper and metal screen or lath are typically placed against the wall and attached by nails to the studs. A plurality of spacers, such as furring strips or dimples in the additional screen sections, are provided between the boards and the additional wire screen sections to allow the subsequent plaster layer to flow into the openings of the wire screen sections and fill the space between the screens and the top of the boards. Plaster is then typically applied by hand using a hawk and trowel method or applied with a nozzle connected to a machine as described above.
With reference to FIG. 10C, an additional improvement to the previous art method is shown. Guide edge members are attached, typically by nailing into the form boards, to the edges of the wire screen sections over the plaster form boards. The guide edges are spaced apart from and aligned to be parallel with the plaster form boards. The guide edge members provide a guide to the trowel or plaster dispensing nozzle as the plaster is applied, thereby allowing a uniform depth of plaster to be applied easily. Representative guide edge members used in the trade are made from 14 gauge wire such as the xe2x80x9cCEMCORNERxe2x80x9d corner reinforcement made by Cemco, Covina Lane, CA. Or the xe2x80x9cComerAidxe2x80x9d cover nose wire made by Stockton Products, Burbank, Calif.
The above-described method requires a number of hand operations, such a nailing the boards, cutting the additional wire screen sections, hand forming the screen sections over the boards and attaching the guide edge members, which significantly increases the cost of applying plaster relief bands. It would be an advantage to provide a system to reduce the number of hand operations required to apply plaster relief bands.
It is important to select boards made of wood which are of uniform cross section, in order to achieve a visually pleasing effect. Boards which are not uniform in thickness or width will show angular offsets at the ends where they meet. It is also important to select wood which is well cured and has stable dimensional shape. If the wood twists or otherwise deforms after the plaster has dried, unsightly cracks may appear. Cracks may also allow moisture to penetrate the plaster and attack the wood beneath, or provide additional unwanted access to wood destroying pests. Boards of suitable quality currently sell for $2 to $3 per linear foot. On a double band board structure, the cost could be from $15 to $18 per linear foot, after including the costs of boards, lath application and finished plaster.
The use of wood for forming the support structure for the plaster of decorative bands is well known in the trade. As the costs of wood continue to increase, and the availability of high quality boards continues to diminish, there is an urgent need to provide an alternative low cost structure which will satisfy the desire for aesthetic enhancements to the various stucco and plaster styles of home and office.
The non-uniformity of wooden boards in width and thickness can cause unsightly mismatch in the appearance of the relief bands on a home. Either higher quality and thus higher cost boards must be purchased, or labor intensive and expensive modification must be made on the job site. This slows down the assembly process and further adds to the cost of building. It would be an advantage to provide a support structure for plaster relief bands which would guarantee uniformity in cross section aspect and thus match precisely when aligned at the ends.
The weight of the wood used for the band support structure creates several concerns. Handling and aligning long lengths of boards takes considerable strength and capability. Moving and holding a 12 foot length of board may require two workers to align successive boards. The cost of shipping the wood used in making the band supports is also a factor in the cost of building plaster or stucco homes. Wood often is shipped in a condition wherein it contains an appreciable amount of water which significantly increases the weight of the wood. Wood typically contains 30% or more water by weight. Such additional weight is of no use and in fact may be harmful as described above. Wood used for decorative support may also be stored outdoors while awaiting construction. It is possible for the wood to absorb moisture from the surroundings thereby increasing its"" weight even if it had been shipped in an originally dry state. It would be an advantage to have a band support structure which is lighter in weight, thereby reducing the cost and time of installation and the cost of shipping to the job site. It would be an additional advantage to provide a band support structure which could not absorb water while stored at a building site.
The use of wood as a building material combined with increased demands from a growing population puts increasing pressure on our forest preserves. It would be an advantage to provide a substitute material which would reduce the need to use wood except where it is most effective, thereby preserving our valuable resources.
Even though the wood for plant on bands is covered by fire-resistant plaster, the building codes still require the bands to be considered flammable structures. It would be an advantage to provide a substitute material which was impervious to fire, and thereby add increased safety to homes and buildings.
The general purpose of the invention is to provide light weight, low cost prefabricated plaster relief form members which can be shipped to a construction job site in final form to simplify the application of relief bands to the exterior of homes and buildings which are to be coated with a cementitous coating, typically plaster or stucco.
According to one embodiment of the invention a prefabricated plaster relief form member is provided for receiving and retaining a fluid cementitious coating, such as plaster, when the member is attached to a prepared structural wall.
The member is configured from an openwork lattice sheet, preferably of an expanded metal lath. The lattice sheet is adapted to receive and retain the plaster when the plaster when the plaster is applied by hand or by spraying with a nozzle of a machine. The lattice sheet is formed into a longitudinal channel having a top with opposed outer edges.
Two spaced apart sides extend away from the respective opposed outer edges, to respective base edges. The respective base edges are aligned parallel to the top such that a mounting plane is defined parallel to the top of the channel.
Two mounting flange portions, each extending outward and away from the base edges of the respective sides, lie within the mounting plane parallel to the channel.
The member is thus defined as a channel having a length between two opposed ends and a width between the two opposed sides. The channel is configured to have an essentially uniform lateral cross section, perpendicular to the longitudinal dimension, protruding away from the mounting plane.
The flange sections are adapted for mounting to the prepared structural wall such that a plurality of such members mounted on the structural wall and adjoined end-to-end form a continuous relief band protruding from the wall. The flange sections may be nailed or stapled to the studs of a prepared wall after adjacent form members are aligned and adjoined end-to-end.
The regular cross section of similar prefabricated form members ensures an aesthetically pleasing effect is easily achieved without shaving, trimming or selecting wooden boards.
The light weight and regular shape of these prefabricated members enable for easy and low cost installation of the support forms needed for applying relief bands to stucco homes and buildings.
The metal lath or lattice work is light, but has sufficient strength to support the plaster coating and hold it in place while it cures. The prefabricated shape enables the construction of plaster relief bands without the use of wood boards and the additional weight and shipping cost involved. The cells and strands of the lattice work provides openings for the plaster to flow and provides a secure network for the plaster to take hold while it hardens.
The uniform shape of the form member is dimensionally stable and not subject to absorbing water. This eliminates the potential of warping that occurs with the use of wood as support members for relief bands.
The combination of the structural support and the open lattice in the one element of the prefabricated form member reduces the labor that otherwise is involved in attaching sheets of screen wire to the wood planks used in conventional construction.
In another embodiment of the prefabricated form member, there is provided at least one edge guide segment parallel to and spaced apart a preselected distance from at least one of the channel outer edges. The edge guide segment is aligned parallel to the length of the member and is configured to provide a guide edge for a tool. A connecting frame is provided for rigidly connecting the edge guide segment to the member such that the edge guide segment provides a secure guide edge for a tool used to apply the plaster or stucco coating to a preselected thickness along the length of the member. A preferred thickness of plaster coating is about xe2x85x9e inch minimum in the finished state.
The prefabricated form member is typically formed from expanded, galvanized metal having a preformed weight of about 3.4 pounds per square yard. The lattice is shaped into an array of elongated hexagons, the hexagons having a major axis of about xc2xd inch and a minor axis of about xe2x85x9c inch. The adjacent hexagons along the minor axis being connected at opposed sides by respective common side segments of about xe2x85x9 inch in length, and adjacent hexagons along the major axis being connected at the ends of respective xe2x85x9c inch common end segments, while the respective side and end segments are connected by corresponding right and left angled linking segments.
A prefabricated form member as described above is non-permeable to water, non-flammable and semi-rigid and has a lateral strength sufficient to support a plaster coating having a thickness from about xc2xd inch in thickness, to about 2 inches in thickness.
It is an advantage in accordance with this invention to provide plaster relief form members which eliminate the use of lumber in achieving architectural enhancement effects.
It is a further advantage in accordance with this invention to provide plaster relief form members which reduce cost of installation.
It is a further advantage in accordance with this invention to provide plaster relief form members which are lower in weight than equivalent lumber elements.
It is a further advantage in accordance with this invention to provide plaster relief form members which reduce the cost of shipping members to the job site.
It is a further advantage in accordance with this invention to provide plaster relief form members which are uniform in cross section and impervious to warping or cracking.
It is a further advantage in accordance with this invention to provide plaster relief form members which reduce the number of hand operations and thereby reduce the cost of installation.
It is a further advantage in accordance with this invention to provide plaster relief form members which are non-flammable.
It is a further advantage in accordance with this invention to provide plaster relief form members which may be mass-produced in a wide variety of standard shapes at low cost.
It is a further advantage in accordance with this invention to provide plaster relief form members which can be easily joined end-to-end to form visually uniform relief bands on outer walls, around door or window openings and along the facia of a building. The relief bands have stable shape with age and are resistant to warping and cracking due to moisture absorption/desorption.
It is a further advantage of the present invention to use welded wire lath to form the form member absent any other structural support member.
It is a further advantage to add edge guides to the welded wire form member.
It is a further advantage to form the member out of rib lath, preferably by placing the rib members at the comers of the top and sides of the channel and in addition to depress the top from the comers so that the ribs provide edge guides, and absent any other structural support member.
It is a further advantage to form the member out of woven wire lath also known as chicken wire, and preferably of the self furring form, absent any other structural support member, and in addition, preferably with edge guides applied to the comers of the top and side of the channel.
It is a further advantage, where edge guides applied to comers of the top and sides of the channel are cut-down to have shorter side extensions.